Conventional vehicular car doors employ individual OFF and ON pushbutton type switches mounted in door sills of vehicles to detect when the door is open, ajar or closed. Separate wires route from each switch to a central control unit which will receive the signal and then issue command signals to circuits that will illuminate the courtesy light of the vehicle if the door is open and will cause a door ajar indicator to respond if the door is in an ajar condition.
Such a system requires several wires to be routed through door post and pillar post of the vehicle.
Knowing that sensor communication technology is available, as evidenced in U.S. Pat. No. 4,736,367 entitled "Smart Control And Sensor Devices Single Wire Bus Multiplex System" which issued Apr. 5, 1988, the present inventors sort ways and means to apply such technology to vehicle door latches. That search resulted in the improved door latch system of the present invention.
SUMMARY OF THE INVENTION
Smart sensors mounted in a door latch mechanism for detecting when the door latch is in an open or a door-ajar condition provide electrical signals to a sensor communication network over a single wire bus. The sensor network generates commands from the electrical signals for commanding door-ajar and door-open indicators and light driver circuits to turn on the respective indicator and lights. When the door is ajar, only the ajar indicator illuminates. When the door is open, both the ajar indicator and the courtesy light in the vehicle turns on.